An Etymological Dictionary of the German Language/kosen
kosen, vb., ‘to chat, caress,’ from MidHG. kôsen, OHG. chôsôn, ‘to converse, talk.’ The meaning of the vb. is opposed to any connection with OHG. chôsa, ‘lawsuit,’ and Lat. causa, causari, for it nowhere shows an indication of a legal origin; ModFr. causer, ‘to chat,’ is also derived from G., since in Lat. causa, Fr. chose originated. As a native word kosen (Goth. *kausôn) is of uncertain origin; it is certainly connected, however, with AS. ceást, MidE. cheeste, ‘argument, dispute,’ Du. keuzelen, ‘to caress.’